Visualizing and Understanding ATLAS Calorimeters with Atlantis

We describe tools that have been developed for the visualization and understanding of the hadronic and electromagnetic calorimeters of the ATLAS experiment with the event visualization program Atlantis. The event data is extracted into XML format by dedicated algorithms running within the ATLAS Software framework ATHENA, and read into Atlantis directly from physical datafiles or via a server/client-setup. For the ATLAS Calorimeters commissioning, code was developed to create XML-data with detailed calorimeter information, like the electronic pulse shapes, calibration factors and cell identifiers. All this information is displayed in Atlantis through tools developed for this purpose. With these new features, the user has access to the reconstructed and raw data in the same place, and can check for example the consistency of the reconstruction. It allows easy identification of problematic calorimeter cells, e.g. high noise or dead cells, and also allows one to compare digital data from calorimeter and trigger channels, and was used during the ATLAS detector commissioning in 2008 and 2009.